丰林自然保护区3种典型森林类型对降雪、积融雪过程的影响

Influence of Three Typical Forest Types on Processes of Snowfall,Snow Cover and Snow Melting in Fenglin National Nature Reserve

选择小兴安岭丰林自然保护区内的云冷杉红松林、云冷杉林和白桦林3种典型林分类型为研究对象,选取不同林分类型的典型地段设置样地,通过量雪槽、量雪桥、量雪器测定林内外降雪和积雪的深度、密度及雪水当量,进行了林分内外降雪、积雪和融雪过程的对比研究。结果表明,受叶面积指数的影响,云冷杉林的截雪量最大,积雪保存率最高;云冷杉红松林的截雪量和保存率次之,白桦林最小;林外草地最大积雪厚度最高,其次为白桦林,再次为云冷杉林及云冷杉红松林;林内外积雪融化时间均在2月初,3月中旬积雪消融速率加快,其中常绿的云冷杉林和云冷杉红松林融雪持续时间可达60d,较林外草地和落叶白桦林多延长5-20d;另外,林内的降雪和积雪密度大多均小于林外（平均为0.113g/cm3）,差异不显著（P〉0.05）。总之,林分内外及不同林分类型之间的雪水文过程具有明显差异,森林对降雪具有明显的截留作用,并可延长积融雪过程,特别是常绿针叶林,其原因除受叶面积指数或郁闭度的影响外,可能与冠层结构、气候变化、地形因素和积雪性质等有关。

Three typical forest types（Korean pine-spruce-fir forest,spruce-fir forest,and birch forest）in Fenglin national nature reserve of Xiaoxing＇an Mountains were chosen as research objects,and the representative sections of each forest type were selected to establish sample plots.We measured the snow depth,snow density and snow water equivalent of snowfall and snow cover inside and outside forests by using snow slot,snow bridge and snow gauge,and compared the processes of snowfall,snow cover and snow melting inside and outside forests.The results showed that due to the influence of leaf area index（LAI）,the interception of snowfall and snow retention rate of 3forest types listed in the following order：spruce-fir forestKorean pine-spruce-fir forestbirch forest,while the maximum snow depth listed in the following order：grassland outside forestbirch forestspruce-fir forest and Korean pine-spruce-fir forest.The accumulated snow inside and outside forests started to melt in early February,and in mid-March,snow ablation rate accelerated.The snow melting duration could last up to 60 days in evergreen spruce-fir forest and Korean pine-spruce-fir forest,which was 5to 20 days more than snow melting duration in grassland and broadleaved birch forest.In addition,the snowfall and snow cover density in forests（0.113g/cm3）were less than those in grassland outside forests,but the differences were not significant（P〉0.05）.In conclusion,the snow hydrological processes were apparently different inside and outside forests and were also different among different forest types.Forests,especially evergreen coniferous forest,could intercept snowfall and prolong the process of snow melting,which probably related with the influences of leaf area index or crown density,and might also related with the canopy structure,climate change,terrain factors,snow characteristics,and so on.